Researchers have determined what happens to people’s liver when they are exposed to PFAS. A researcher says that these substances, which almost everyone has in their bodies, increase the risk of developing type 2 diabetes and metabolic dysfunction–associated steatotic liver disease.
In recent years, the focus on how PFAS can harm human health has been increasing.
PFAS are industrial chemicals used in many everyday products, including paint, cosmetics, waterproof fabrics, electronics, ski wax, carpets and firefighting foams.
When people are exposed to PFAS – which everyone is – this can increase the risk of developing various diseases such as type 2 diabetes and metabolic dysfunction–associated steatotic liver disease, but researchers have not fully understood why PFAS have this effect on health until now.
However, researchers have improved their understanding in a new study in which they determined how liver cells change when exposed to PFAS.
The research contributes to understanding the health hazards posed by PFAS and indicates how the levels of PFAS in the human body might be reduced.
“Our results provide insight into what happens in the human liver when people are exposed to PFAS, and we have found how PFAS affects various signalling pathways that influence health. Understanding how PFAS affects the body also leads to more knowledge about how to get PFAS out of the body again,” explains a researcher behind the study, Tuulia Hyötyläinen, Professor, School of Science and Technology, Örebro University, Sweden.
The research has been published in Environment International.
Some people are exposed to huge quantities of PFAS
PFAS are ubiquitous in the environment, but some places have more than others, so people are exposed to different quantities of PFAS. Food is also a major source of PFAS exposure.
For example, the town of Korsør, Denmark has a training area for firefighters, and large quantities of PFAS-containing firefighting foams have been used there.
However, rain spread PFAS from the training area to the surrounding fields where cows were grazing.
People in Korsør ate these cows and therefore have very high concentrations of PFAS in their blood.
PFAS are well recognised as being hazardous to human health, including weakening the immune system and damaging the liver. However, exactly what PFAS do that is so harmful remains unclear.
Research has indicated that PFAS disturbs the liver and the composition of health-promoting intestinal bacteria.
Examined liver cells using advanced methods
In the new study, Tuulia Hyötyläinen and colleagues aimed to determine what happens in people’s livers at different concentrations of PFAS by exposing liver cells from both men and women to a wide spectrum of doses of PFAS, all of which had previously been found in humans.
The researchers then determined the concentration of all metabolites such as lipids, sugars and bile acids in the examined cells (metabolomics) and used high-resolution images with cell staining to identify how PFAS affect various signalling pathways in the liver cells and their phenotype.
“We aimed to improve the mechanistic understanding of these processes to determine how exposure to PFAS affects health and the risk of developing disease,” says Tuulia Hyötyläinen.
PFAS disturb many systems
The study revealed distinct changes in many crucial signalling pathways in the liver cells. These included signalling pathways affecting oxidative stress, inflammation and lipid metabolism, amino acids, steroids and sugars.
One change involved downregulating bile acids, which have an important role in fat metabolism.
The researchers also found that PFAS affect organelles: miniature organs inside the cells.
These included changes in the form and function of the mitochondria, F-actinin the cells’ cytoskeleton – the Golgi apparatus – which has an important role in designing proteins and in the plasma membrane.
Further, the researchers found no linear relationship between the amount of PFAS applied to the liver cells and the degree of change, but the relationship was nevertheless dose-dependent.
“We found clear changes in metabolic signalling pathways that correlate well with the effects found for humans and in studies of people exposed to PFAS. Overall, we now have a better sense of which signalling pathways PFAS affects and how this can lead to disease,” notes Tuulia Hyötyläinen.
PFAS also harm indirectly
Tuulia Hyötyläinen says that another interesting aspect of the study is that, although the researchers found many effects that match well with the results of human studies, the researchers could not find some effects in humans in the liver cells.
This indicates that PFAS can not only directly but also indirectly affect the liver and the general health of people.
One indirect effect of PFAS may be on the gut microbiome, which then sends different signals to the liver. This was observed in studies with humans but not in studies of liver cells exposed to PFAS
Important to screen for harmful effects
The researchers will continue more studies on the effects of exposure to PFAS – including animal studies.
The researchers also aim to improve their understanding of how the body tries to remove PFAS, and according to Tuulia Hyötyläinen, bile acids seem to be part of the solution.
“Some bile acid treatments might help to remove PFAS from the body. We can use this especially for people who have been exposed to a high dose of PFAS,” explains Tuulia Hyötyläinen.
She elaborates that combining studies of cells and humans is indispensable to learn more about how not only PFAS but also other chemicals affect health.
“We need some models that make screening for the health effects of common chemicals easier. We would like to be able to test them more rapidly and preferably before they are in all our bodies,” concludes Tuulia Hyötyläinen.
